Not Applicable.
1. Field of the Invention
The present invention generally relates to a radiopharmaceutical pig and apparatus for transporting radioactive substances, specifically radiopharmaceuticals.
2. Discussion of Related Art
Generally, radioactive drugs are in a liquid form suitable for injection into a patient. Because of the radioactive characteristics of these drugs, they must be handled according to regulations promulgated by various departments of the United States government, including the Department of Transportation (DOT), the Nuclear Regulatory Commission, and the Occupational Health and Safety Administration (collectively xe2x80x9cfederal regulationxe2x80x9d). Federal regulation guidelines presently require that a radioactivity reading on the outside surface of a shipping container housing radioactive substances be less than 50 mRems/hour and a reading taken at a distance of 1 meter from the outside surface of the container should be less than 1 mRems/hour in order for the container with the radioactive substance to be classified as a Yellow-II package. It is desirable to have packages conform to Yellow-II package guidelines.
In the nuclear medicine and radiopharmaceutical industries, radioactive drugs are used for various applications, including the internal imaging of various human organs for diagnostic purposes. Among the various modalities of internal radioactive imaging, Positron Emission Tomography (PET) is a relatively recent imaging method that falls within the sphere of nuclear medicine. Nuclear medicine is an imaging modality in which radioactive material is injected into a patient rather than using an external radioactive source. Whereas traditional diagnostic techniques such as X-rays, computerized tomography scans, or magnetic resonance imaging produce static images of the body""s anatomy or structure, PET is a diagnostic imaging technology used to measure metabolic human cell activity. In this manner, cancer cells can be visualized before they are large enough to be detected as a structure. Additionally, PET imaging can identify cancerous structures prior to surgery. PET is used not only to diagnose and manage patients with cancer but also is used for patients with neurological disorders and heart disease.
Fluorodeoxyglucose tagged with Fluorine-18 as a marker (xe2x80x9cFDG F18xe2x80x9d) is the most common short-lived radiopharmaceutical substance used in PET. Because FDG F18 allows accurate and precise diagnoses of tumors at their early stages, it is considered to be the solution of choice for the diagnosis of cancer and for monitoring a patient""s response to cancer treatment.
FDG F18 is injected into the patient and through the natural metabolic differentiation in absorption allows cancerous tissues to be identified because cancerous tissue has a higher metabolic rate than that of surrounding healthy tissue.
FDG F18 has a high radioactive energy with about a two hour half life. A single dose of FDG F18 usually requires up to 15 millicuries (mCi) of FDG F18. Thus, if a shipment of FDG F18 will be administered into a patient by a nuclear medical facility ten hours after its shipment from the radiopharmaceutical manufacturer, an initial dose of about 480 mCi must be shipped. Radiopharmaceutical manufacturers however, desire systems that could accommodate initial doses as high as about 700 mCi FDG F18.
One type of delivery container currently used for the delivery of syringes containing radioactive drugs is known as a radiopharmaceutical pig. The radiopharmaceutical pig typically includes a two-part assembly and has an inner chamber suitable for carrying a syringe. The chamber is lined with a radiation shielding material, usually elemental lead, although other materials such as tungsten have been used. The exterior of the radiopharmaceutical pig is generally a shell made out of polystyrene, polypropylene, metal or other suitable materials well known to one skilled in the art. The pig is then placed into a cylindrical sealed lead enclosure.
One such device is presently manufactured by Biodex Medical Systems, Inc. This apparatus includes a pig wherein the thicknesses of the pig""s wall, upper and lower portions contain approximately xc2xdxe2x80x3 lead. A syringe containing a radiopharmaceutical substance is placed inside the pig. The pig is then placed in another sealed cylindrical lead enclosure which is located within a polyethylene shipping container to meet federal requirements for a maximum radioactivity level detectable at the outside of the container surface not to exceed 50 mRems/hour. With this apparatus, the total weight of the pig with the syringe and cylindrical lead enclosure, reaches about 50 lbs. for radioactive doses of up to about 95 mCi. This is considered the maximum desirable weight for shipping and handling, for preventing possible injury to persons handling the shipping container and for limiting shipping costs. If greater initial doses are required, the combined weight of the pig, the lead enclosure and syringe exceeds 50 lbs. because a heavier pig containing thicker lead is used to provide the required shielding from radioactivity. This weight exceeds the acceptable and desirable levels for the reasons specified above. Thus, because of the ever increasing pressure to reduce medical costs, an inexpensive pig would be beneficial to the health care system and would also ultimately benefit the recipients of such radiopharmaceutical medical treatments.
There are pigs and cylindrical lead enclosures available today that can accommodate up to three syringes, each syringe containing a single dose, in a single pig. The problem with these pigs and enclosures is that there is significant radioactivity hand exposure. When the top lid of one of the lead enclosures is opened, the pig exposes the radioactive substances in each of the syringes. Because all three doses are housed in a single pig.
Accordingly, there is a need for a lightweight, radiopharmaceutical transportation apparatus that weighs less than 50 lbs. and also limits an amount of radioactivity that penetrates to the surface of the apparatus so that the amount of radioactivity detectable on the outside surface of the apparatus is less than about 50 mRems/hour. There is a further need for a radiopharmaceutical transportation apparatus that accommodates multiple doses of radioactive substances, weighs less than about 50 lbs. and adequately shields against radioactivity including radioactivity exposure to the hands when the container is opened. There is also a need for a radiopharmaceutical transportation apparatus that can hold up to 700 mCi of a radioactive substance, weighs less than 50 lbs. and still limits an amount of radioactivity penetrating the outside surface of the apparatus to a level of radioactivity less than 50 mRems/hour.
An aspect of the present invention resides in an improved pig and radiation shield for transporting radioactive substances. The pig has an elongated sidewall between two closed ends. The two closed ends are thicker than the sidewall and contain greater amounts of lead shielding. The pig defines a chamber bounded by the sidewall and closed ends. The pig separates into two halves to that when separated, a syringe containing a radioactive substance may be inserted into the chamber. The two halves of the pig are then closed to seal the syringe within the chamber. The radiation shield is elongated and open at its two ends to define a cavity, into which is placed the pig. The two closed ends of the pig may protrude through both open ends of the radiation shield simultaneously or they could be even with the open ends or fall short of reaching the open ends. The combination of shielding of the pig and shielding of the radioactive shield provide sufficient radiation penetration resistance so that Yellow-II package guidelines are met.